Lens curvature variation apparatus

ABSTRACT

The present invention relates to a lens curvature variation apparatus. The lens curvature variation apparatus according to an embodiment is a lens curvature varying apparatus for varying a curvature of a liquid lens having a variable curvature based on an applied electric signal, the lens curvature varying apparatus comprising: And a control unit for controlling the lens driving unit to form a target curvature of the liquid lens on the basis of the sensed curvature, The sensor unit senses a change in the size or the area of the boundary area between the insulator on the electrode in the liquid lens and the electroconductive aqueous solution. Thereby, the curvature of the lens can be sensed quickly and accurately.

TECHNICAL FIELD

The present invention relates to a lens curvature variation apparatus,and more particularly, to a lens curvature variation apparatus capableof quickly and accurately sensing the curvature of a lens.

BACKGROUND ART

A lens is a device that diverts a path of light. Lenses are used in avariety of electronic devices, especially in cameras.

Light passing through a lens in a camera is converted into an electricalsignal through an image sensor, and an image can be acquired based onthe electrical signal obtained through conversion.

In order to adjust the focus of an image to capture, it is necessary tovary the position of the lens. However, when the camera is employed in asmall electronic device, a considerable space needs to be secured tovary the position of the lens, which results in inconvenience.

Accordingly, an approach for adjusting the focus of an image to capturewithout varying the position of the lens is being studied.

DISCLOSURE OF INVENTION Technical Problem

Therefore, the present invention has been made in view of the aboveproblems, and it is an object of the present invention to provide a lenscurvature variation apparatus capable of quickly and accurately sensingthe curvature of a lens.

It is another object of the present invention to provide a lenscurvature variation apparatus capable of quickly and accurately varyingthe curvature of a lens.

Solution to Problem

In accordance with an aspect of the present invention, the above andother objects can be accomplished by the provision of a lens curvaturevariation apparatus for varying a curvature of a liquid lens based on anapplied electrical signal, the lens curvature variation apparatusincluding a lens driver to apply the electrical signal to the liquidlens, a sensor unit to sense the curvature of the liquid lens formedbased on the electrical signal, and a controller to control the lensdriver to form a target curvature of the liquid lens based on the sensedcurvature, wherein the sensor unit senses a size of an area of aboundary region between an insulator on an electrode and anelectroconductive aqueous solution in the liquid lens or a change in thesize.

Advantageous Effects of Invention

As is apparent from the above description, A lens curvature variationapparatus according to an embodiment of the present invention isconfigured to vary the curvature of a liquid lens which is variablebased on an applied electrical signal, and includes a lens driver toapply an electrical signal to a liquid lens, a sensor unit to sense thecurvature of the liquid lens formed based on the electrical signal, anda controller to control the lens driver to form a target curvature ofthe liquid lens based on the sensed curvature. The sensor unit mayquickly and accurately sense the curvature of the lens by sensing thesize of the area of the boundary region between an insulator on anelectrode and an electroconductive aqueous solution in the liquid lensor a change in the size.

In particular, the curvature of the lens may be accurately detected bysensing a capacitance corresponding to the size of the area of theboundary region between the insulator on the electrode and theelectroconductive aqueous solution in the liquid lens or a change in thesize.

The sensor unit may sense the capacitance corresponding to the size ofthe area of the boundary region between the insulator on the electrodeand the electroconductive aqueous solution in the liquid lens or a orchange in the size, and feed back the capacitance to apply an electricalsignal to the liquid lens such that the curvature of the lens is varied.Thereby, the curvature of the lens may be varied quickly and accurately.

The lens curvature variation apparatus may include a plurality ofconductive lines for supplying a plurality of electrical signals outputfrom the lens driver to the liquid lens, and a switching elementdisposed between one of the plurality of conductive lines and the sensorunit, and the sensor unit may sense the size of the area of the boundaryregion between the insulator on the electrode and the electroconductiveaqueous solution in the liquid lens or a or change in the size during anON period of the switching element. Thereby, the curvature of the lensmay be sensed quickly and accurately.

The lens curvature variation apparatus may include an equalizer tocalculate a curvature error based on the calculated curvature and thetarget curvature, and a pulse width variation controller to generate andoutput a pulse width variation signal based on the calculated curvatureerror. Thereby, the curvature of the lens may be sensed quickly andaccurately.

BRIEF DESCRIPTION OF DRAWINGS

The above and other objects, features and other advantages of thepresent invention will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings, in which:

FIG. 1A is a cross-sectional view of the camera according to anembodiment of the present invention;

FIG. 1B is an internal block diagram of the camera of FIG. 1A;

FIG. 2 is a view illustrating a lens driving method;

FIGS. 3A and 3B are views illustrating a method of driving a liquidlens;

FIGS. 4A to 4C are views showing the structure of a liquid lens;

FIGS. 5A to 5E are views illustrating variation of the lens curvature ofa liquid lens;

FIG. 6 is an exemplary internal block diagram of a camera related to thepresent invention;

FIG. 7 is an exemplary internal block diagram of a camera according toan embodiment of the present invention;

FIGS. 8A to 12B are views referred to in the description of FIG. 7;

FIG. 13A is an exemplary internal block diagram of a camera according toanother embodiment of the present invention;

FIG. 13B is an exemplary internal block diagram of a camera according toyet another embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers will be usedthroughout the drawings to refer to the same or like parts.

As used herein, the suffixes “module” and “unit” are added or usedinterchangeably to facilitate preparation of this specification and arenot intended to suggest distinct meanings or functions. Accordingly, theterms “module” and “unit” may be used interchangeably.

FIG. 1A is a cross-sectional view of the camera according to anembodiment of the present invention.

First, FIG. 1A is an example of a cross-sectional view of the camera195.

The camera 195 may include aperture 194, lens 193 and image sensor 820.

The aperture 194 may obstruct or allow light incident on the lens 193.

The image sensor 820 may include an RGB filter 910 and sensor array 911to convert an optical signal into an electrical signal to sense RGBcolors.

Accordingly, the image sensor 820 may sense and output RGB image.

FIG. 1B is an internal block diagram of the camera of FIG. 1A.

Referring to FIG. 1B, the camera 195 may include lens 193 and imagesensor 820, and an image processor 830.

The image processor 830 may generate an RGB image based on theelectrical signal from the image sensor 820.

The exposure time may be adjusted based on the electrical signals fromthe image sensor 820.

FIG. 2 is a view illustrating a lens driving method.

FIG. 2(a) illustrates that light from the focus point 401 is transmittedto the lens 403, the beam splitter 405, the microlens 407, and the imagesensor 409, and thus an image PH having a size Fa is formed on the imagesensor 409.

Particularly, FIG. 2(a) illustrates that the focus is correctly formedin correspondence with the focus point 401.

Next, FIG. 2(b) illustrates that the lens 403 is shifted toward thefocus point 401, as compared to FIG. 2A, and an image PH having a sizeFb less than Fa is focused on the image sensor 409.

Particularly, FIG. 2(b) illustrates that the focus is formed excessivelyahead in correspondence with the focus point 401.

Next, FIG. 2(c) illustrates that the lens 403 is shifted away from thefocus point 401, and thus an image PH having a size Fc greater than Fais focused on the image sensor 409.

Particularly, FIG. 2(c) illustrates that the focus is formed excessivelybehind in correspondence with the focus point 401.

That is, FIG. 2 illustrates varying the position of the lens to adjustthe focus of a captured image.

As shown in FIG. 2, a voice coil motor (VCM) is used to vary theposition of the lens 403.

However, the VCM requires a considerable space for movement of the lenswhen it is used in a small electronic device such as the mobile terminalof FIG. 1.

In the case of the camera 195 used in the mobile terminal, an opticalimage stabilization (OIS) function is required in addition toautofocusing.

Since the VCM allows only one-dimensional movement in a direction suchas the left-right direction as shown in FIG. 2, it is not suitable tostabilize the image.

In order to address this issue, the present invention uses a liquid lensdriving system instead of the VCM system.

In the liquid lens driving system, the curvature of the liquid lens isvaried by applying an electrical signal to the liquid lens, andtherefore the lens need not be shifted for autofocusing. In addition, inimplementing the image stabilization function, the liquid lens drivingsystem may prevent blurring in two dimensions or three dimensions.

FIGS. 3A and 3B are views illustrating a method of driving a liquidlens.

First, FIG. 3A(a) illustrates that a first voltage V1 is applied to aliquid lens 500, and the liquid lens operates as a concave lens.

Next, FIG. 3A(b) illustrates that the liquid lens 500 does not changethe travel direction of light as a second voltage V2, which is greaterthan the first voltage V1, is applied to the liquid lens 500.

Next, FIG. 3A(c) illustrates that the liquid lens 500 operates as aconvex lens as a third voltage V3, which is greater than the secondvoltage V2, is applied to the liquid lens 500.

While it is illustrated in FIG. 3A that the curvature or diopter of theliquid lens changes according to the level of the applied voltage,embodiments of the present invention are not limited thereto. Thecurvature or diopter of the liquid lens may be varied according to apulse width of an applied pulse.

Next, FIG. 3B(a) illustrates that the liquid in the liquid lens 500 hasthe same curvature and operates as a convex lens.

Referring to FIG. 3B(a), incident light Lpaa is converged, andcorresponding output light Lpab is output.

Next, FIG. 3B(b) illustrates that the traveling light is diverted upwardas the liquid in the liquid lens 500 has an asymmetric curved surface.

Referring to FIG. 3B(b), the incident light Lpaa is converged upward,and the corresponding output light Lpac is output.

FIGS. 4A to 4C are views showing the structure of a liquid lens.Particularly, FIG. 4A is a top view of a liquid lens, FIG. 4B is abottom view of the liquid lens, and FIG. 4C is a cross-sectional viewtaken along line I-I′ in FIGS. 4A and 4C.

Particularly, FIG. 4A corresponds to the right side surface of theliquid lens 500 in FIGS. 3A and 3B, and FIG. 4B corresponds to the leftside surface of the liquid lens 500 in FIGS. 3A and 3B.

Referring to the drawings, a common electrode (COM) 520 may be disposedon the liquid lens 500, as shown in FIG. 4A. The common electrode (COM)520 may be arranged in a tubular shape, and the liquid 530 may bedisposed in a region under the common electrode (COM) 520, particularly,a region corresponding to the hollow.

Although not shown in the figures, an insulator (not shown) may bedisposed between the common electrode (COM) 520 and the liquid toinsulate the common electrode (COM).

As shown in FIG. 4B, a plurality of electrodes (LA to LD) 540 a to 540 dmay be disposed under the common electrode (COM) 520, particularly underthe liquid 530. In particular, the plurality of electrodes (LA to LD)540 a to 540 d may be arranged so as to surround the liquid 530.

A plurality of insulators 550 a to 550 d for insulation may be disposedbetween the plurality of electrodes (LA to LD) 540 a to 540 d and theliquid 530.

That is, the liquid lens 500 may include the common electrode (COM) 520,the plurality of electrodes (LA to LD) 540 a to 540 d spaced apart fromthe common electrode (COM), and the liquid 530 and an electroconductiveaqueous solution 595 (see FIG. 4C) disposed between the common electrode(COM) 520 and the plurality of electrodes (LA to LD) 540 a to 540 d.

Referring to FIG. 4C, the liquid lens 500 may include a plurality ofelectrodes (LA to LD) 540 a to 540 d on a first substrate 510, aplurality of insulators 550 a to 550 d for insulation of the pluralityof electrodes (LA to LD) 540 a to 540 d, a liquid 530 on the pluralityof electrodes (LA to LD) 540 a to 540 d, an electroconductive aqueoussolution 595 on the liquid 530, a common electrode (COM) 520 spacedapart from the liquid 530, and a second substrate 515 on the commonelectrode (COM) 520.

The common electrode 520 may be formed in a tubular shape with a hollow.The liquid 530 and the electroconductive aqueous solution 595 may bedisposed in the hollow region. The liquid 530 may be arranged in acircular shape, as shown in FIGS. 4A and 4B. The liquid 530 may be anonconductive liquid such as oil.

The size of the cross section of the hollow region may increase as itextends from the lower portion thereof to the upper portion thereof, andthus The lower portion of the plurality of electrodes (LA to LD) 540 ato 540 d may be larger than the upper portion of the plurality ofelectrodes (LA to LD) 540 a to 540 d.

In FIG. 4C, the first electrode (LA) 540 a and the second electrode (LB)540 b among the plurality of electrodes (LA to LD) 540 a to 540 d arearranged to be inclined, and the lower portion thereof is large than theupper portion thereof.

As an alternative to the example of FIGS. 4A to 4C, the plurality ofelectrodes (LA to LD) 540 a to 540 d may be arranged at an upperposition, and the common electrode 520 may be arranged at a lowerposition.

While FIGS. 4A to 4C illustrates that four electrodes are provided,embodiments are not limited thereto. Two or more electrodes may beformed.

In FIG. 4C, if a pulse-like electrical signal is applied to the firstelectrode (LA) 540 a and the second electrode (LB) 540 b a predeterminedtime after a pulse-like electrical signal is applied to the commonelectrode 520, a potential difference is made between the commonelectrode 520, the first electrode (LA) 540 a and the second electrode(LB) 540 b. Then, the shape of the electroconductive aqueous solution595 having electrical conductivity changes, and the shape of the liquid530 in the liquid lens changes according to the change in shape of theelectroconductive aqueous solution 595.

The present invention provides a method of simply and quickly sensingthe curvature of the liquid 530 formed according to electrical signalsapplied to the plurality of electrodes (LA to LD) 540 a to 540 d and thecommon electrode 520.

According to the present invention, the sensor unit 962 senses the sizeof the area of the boundary region Ac0 between the first insulator 550 aon the first electrode 540 a and the electroconductive aqueous solution595 in the liquid lens 500 or a change in the size.

In FIG. 4C, AM0 is exemplarily given as the area of the boundary regionAc0. In particular, it is illustrated that the area of the boundaryregion Ac0 that contacts the electroconductive aqueous solution 595 inthe inclined portion of the first insulator 550 a on the first electrode540 a is AM0.

In FIG. 4C, it is illustrated that the liquid 530 is neither concave norconvex, but is parallel to the first substrate 510 and the like. Thecurvature given in this case may be defined as 0, for example.

As shown in FIG. 4C, for the boundary region Ac0 contacting theelectroconductive aqueous solution 595 in the inclined portion of thefirst insulator 550 a on the first electrode 540 a, the capacitance Cmay be formed according Equation 1.

$\begin{matrix}{C = {ɛ\frac{A}{d}}} & \left\lbrack {{Equation}\mspace{14mu} 1} \right\rbrack\end{matrix}$

Here, ε denotes the dielectric constant of a dielectric 550 a, A denotesthe area of the boundary region Ac0, and d denotes the thickness of thefirst dielectric 550 a.

Here, when it is assumed that E and d have fixed values, the area of theboundary region Ac0 may greatly affect the capacitance C.

That is, as the area of the boundary region Ac0 increases, thecapacitance C formed in the boundary region Ac0 may increase.

In the present invention, since the area of the boundary region Ac0 isvaried as the curvature of the liquid 530 is varied, the area of theboundary region Ac0 or the capacitance C formed in the boundary regionAc0 is sensed using the sensor unit 962.

The capacitance of FIG. 4C may be defined as CAc0.

FIGS. 5A to 5E are views illustrating various curvatures of the liquidlens 500.

FIG. 5A illustrates a case where a first curvature Ria is given to theliquid 530 according to application of an electrical signal to theplurality of electrodes (LA to LD) 540 a to 540 d and the commonelectrode 520.

In FIG. 5A, it is illustrated that the area of the boundary region Aaais AMa (>AM0) as the first curvature Ria is given to the liquid 530. Inparticular, it is illustrated that the area of the boundary region Aaacontacting the electroconductive aqueous solution 595 in the inclinedportion of the first insulator 550 a on the first electrode 540 a isAMa.

According to Equation 1, the area of the boundary region Aaa in FIG. 5Ais larger than that of FIG. 4C, and therefore the capacitance of theboundary region Aaa becomes larger. The capacitance of FIG. 5A may bedefined as CAaa, which is greater than the capacitance CAc0 of FIG. 4C.

The first curvature Ria may be defined as having a value of positivepolarity. For example, the first curvature Ria may be defined as havinga level of +2.

FIG. 5B illustrates a case where a second curvature Rib is formed in theliquid 530 according to application of an electrical signal to theplurality of electrodes (LA to LD) 540 a to 540 d and the commonelectrode 520.

In FIG. 5B, AMb (>AMa) is exemplarily given as the area of the boundaryregion Aba as the second curvature Rib is formed in the liquid 530. Inparticular, it is illustrated that the area of the boundary region Abacontacting the electroconductive aqueous solution 595 in the inclinedportion of the first insulator 550 a on the first electrode 540 a isAMb.

According to Equation 1, the area of the boundary region Aba in FIG. 5Bis larger than that in FIG. 5A, and therefore the capacitance of theboundary region Aba becomes larger. The capacitance of FIG. 5B may bedefined as CAba, which is greater than the capacitance CAaa of FIG. 5A.

The second curvature Rib may be defined as having a value of positivepolarity greater than the first curvature Ria. For example, the secondcurvature Rib may be defined as having a level of +4.

Referring to FIGS. 5A and 5B, the liquid lens 500 operates as a convexlens, thereby outputting output light LP1 a formed by converging theincident light LP1.

Next, FIG. 5C illustrates a case where a third curvature Ric is formedin the liquid 530 according to application of an electrical signal tothe plurality of electrodes (LA to LD) 540 a to 540 d and the commonelectrode 520.

In particular, FIG. 5C illustrates that AMa is given as the area of theleft boundary region Aca, and AMb (>AMa) is given as the area of theright boundary region Acb.

More specifically, the area of the boundary region Aca contacting theelectroconductive aqueous solution 595 in the inclined portion of thefirst insulator 550 a on the first electrode 540 a is AMa, and the areaof the boundary region Acb contacting the electroconductive aqueoussolution 595 in the inclined portion of the second insulator 550 b onthe second electrode 540 b is AMb.

Thus, the capacitance of the left boundary region Aca may be CAaa, andthe capacitance of the right boundary region Acb may be CAba.

In this case, the third curvature Ric may be defined as having a valueof positive polarity. For example, the third curvature Ric may bedefined as having a level of +3.

Referring to FIG. 5C, the liquid lens 500 operates as a convex lens,thereby outputting output light LP1 b by converging the incident lightLP1 further to one side.

Next, FIG. 5D illustrates a case where a fourth curvature Rid is formedin the liquid 530 according to application of an electrical signal tothe plurality of electrodes (LA to LD) 540 a to 540 d and the commonelectrode 520.

In FIG. 5D, AMd (<AM0) is exemplarily given as the area of the boundaryregion Ada as the fourth curvature Rid is formed in the liquid 530. Inparticular, it is illustrated that the area of the boundary region (Ada)contacting the electroconductive aqueous solution 595 in the inclinedportion of the first insulator 550 a on the first electrode 540 a isAMd.

According to Equation 1, the area of the boundary region (Ada) in FIG.5D is smaller than that of FIG. 4C, and therefore the capacitance of theboundary region (Ada) is reduced. The capacitance of FIG. 5D may bedefined as CAda and has a value less than the capacitance CAc0 of FIG.4C.

In this case, the fourth curvature Rid may be defined as having a valueof negative polarity. For example, it may be defined that the fourthcurvature Rid has a level of −2.

Next, FIG. 5E illustrates that the fifth curvature Rie is formed in theliquid 530 according to application of an electrical signal to theplurality of electrodes (LA to LD) 540 a to 540 d and the commonelectrode 520.

In FIG. 5E, AMe (<AMd) is exemplarily given as the area of the boundaryregion Aea when the fifth curvature Rie is formed in the liquid 530. Inparticular, it is illustrated that the area of the boundary region Aeacontacting the electroconductive aqueous solution 595 in the inclinedportion of the first insulator 550 a on the first electrode 540 a isAMe.

According to Equation 1, the area of the boundary region Aea in FIG. 5Eis smaller than that of FIG. 5D, and therefore the capacitance of theboundary region Aea becomes smaller. The capacitance of FIG. 5E may bedefined as CAea, which is less than the capacitance CAda of FIG. 5D.

In this case, the fifth curvature Rie may be defined as having a valueof negative polarity. For example, the fifth curvature Rie may bedefined as having a level of −4.

Referring to FIGS. 5D and 5E, the liquid lens 500 operates as a concavelens, thereby outputting output light LP1 c by diverging the incidentlight LP1.

FIG. 6 is an exemplary internal block diagram of a camera related to thepresent invention.

Referring to FIG. 6, the camera 195 x may include a lens curvaturevariation apparatus 800, an image sensor 820, an image processor 860, agyro sensor 830, and a liquid lens 500.

The lens curvature variation apparatus 800 may include a lens driver860, a pulse width variation controller 840, and a power supply 890.

The lens curvature variation apparatus 800 of FIG. 6 operates asfollows. The pulse width variation controller 840 outputs a pulse widthvariation signal V corresponding to a target curvature, and the lensdriver 860 may output corresponding voltages to the plurality ofelectrodes and the common electrode of the liquid lens 500 using thepulse width variation signal V and the voltage Vx of the power supply890.

That is, the lens curvature variation apparatus 800 of FIG. 6 operatesas an open loop system to vary the curvature of the liquid lens.

According to this method, the curvature of the liquid lens 500 cannot besensed, except that corresponding voltages are output to the pluralityof electrodes and the common electrode of the liquid lens 500 accordingto the target curvature.

In addition, according to the lens curvature variation apparatus 800 ofFIG. 6, when the curvature of the liquid lens 500 needs to be varied toprevent blurring, it may be difficult to accurately vary the curvaturesince the curvature is not sensed.

Therefore, in the present invention, the lens curvature-variable device800 is not implemented as an open loop system as shown in FIG. 6, but isimplemented as a closed loop system.

That is, in order to identify the curvature of the liquid lens 500, thecapacitance formed in the insulator on the electrode in the liquid inthe liquid lens 500 and the boundary region Ac0 contacting theelectroconductive aqueous solution 595 is sensed, and is fed back tocalculate the difference between the target curvature and the currentcurvature and perform a control operation corresponding to thedifference.

Accordingly, the curvature of the liquid lens 500 may be identifiedquickly and accurately, and the curvature of the liquid lens 500 may becontrolled quickly and accurately so as to correspond to the targetcurvature. This operation will be described in more detail withreference to FIG. 7 and subsequent drawings.

FIG. 7 is an exemplary internal block diagram of a camera according toan embodiment of the present invention.

Referring to FIG. 7, a camera 195 m according to an embodiment of thepresent invention may include a lens curvature variation apparatus 900to vary the curvature of a liquid lens 500, an image sensor 820 toconvert light from the liquid lens 500 into an electrical signal, and animage processor 930 to perform image processing based on the electricalsignal from the image sensor 820. image processor

The camera 195 m of FIG. 7 may further include a gyro sensor 915.

The image processor 930 may output focus information AF about an image,and the gyro sensor 915 may output blurring information OIS.

Thus, the controller 970 in the lens curvature variation apparatus 900may determine the target curvature based on the focus information AF andthe blurring information OIS.

The lens curvature control apparatus 900 according to an embodiment ofthe present invention may include a lens driver 960 to apply anelectrical signal to the liquid lens 500, a sensor unit 962 to sense thecurvature of the liquid lens 500 formed based on the electrical signal,and a controller 970 to control the lens driver 960 so as to form atarget curvature of the liquid lens 500 based on the sensed curvature.The sensor unit 962 may sense the size or change in size of the area ofthe boundary region Ac0 between an insulator on an electrode and anelectroconductive aqueous solution 595 in the liquid lens 500. Thus, thecurvature of the lens may be sensed quickly and accurately.

According to an embodiment of the present invention, the lens curvaturevariation apparatus 900 may further include a liquid lens 500 having acurvature varied based on an applied electrical signal.

According to an embodiment of the present invention, the lens curvaturecontrol apparatus 900 may include a power supply 990 to supply power,and an analog-to-digital (AD) converter (not shown) to convert a signalrelated to the capacitance sensed by the sensor unit 962 into a digitalsignal.

The lens curvature variation apparatus 900 may include a plurality ofconductive lines CA1 and CA2 for supplying an electrical signal from thelens driver 960 to each of the electrodes (the common electrode and theplurality of electrodes) in the liquid lens 500 driver, and a switchingelement SWL disposed between the sensor unit 962 and one CA2 of theplurality of conductive lines.

The figure illustrates that the switching element SWL is disposedbetween the sensor unit 962 and the conductive line CA2 for applying anelectrical signal to any one of a plurality of electrodes in the liquidlens 500. In this case, the contact point between the conductive lineCA2 and one end of the switching element SWL or the liquid lens 500 maybe referred to as node A.

In the present invention, an electrical signal is applied to each of theelectrodes (the common electrode and the plurality of electrodes) in theliquid lens 500 through the plurality of conductive lines CA1 and CA2 tosense the curvature of the liquid lens 500. Thus, a curvature may begiven to the liquid 530 as shown in FIGS. 5A to 5E.

For example, during a first period, the switching element SWL may beturned on.

If an electrical signal is applied to the electrodes in the liquid lens500 while the switching element SWL is turned on and is thuselectrically connected with the sensor unit 962, a curvature may beformed in the liquid lens 500, and an electrical signal corresponding tothe curvature may be supplied to the sensor unit 962 via the switchingelement SWL.

Thus, the sensor unit 962 may sense the size of the area of the boundaryregion Ac0 between the insulator on the electrodes and theelectroconductive aqueous solutions 595 in the liquid lens 500 or achange in the size or sense the capacitance of the boundary region Ac0,based on the electrical signal from the liquid lens 500 during the ONperiod of the switching element SWL.

Next, during a second period, the switching element SWL may be turnedoff, and the electrical signal may be continuously applied to theelectrodes in the liquid lens 500. Accordingly, a curvature may beformed in the liquid 530.

Next, during a third period, the switching element SWL may be turnedoff, and no electrical signal or a low-level electrical signal may beapplied to the electrodes in the liquid lens 500.

Next, during a fourth period, the switching element SWL may be turnedon.

If an electrical signal is applied to the electrodes in the liquid lens500 while the switching element SWL is turned on and is electricallyconnected with the sensor unit 962, a curvature may be formed in theliquid lens 500, and an electrical signal corresponding to the curvaturemay be supplied to the sensor unit 962 via the switching element SWL.

If the curvature calculated based on the capacitance sensed during thefirst period is less than the target curvature, the controller 970 maycontrol the pulse width of the pulse width variation control signalsupplied to the driver 960 to be increased in order to obtain the targetcurvature.

Accordingly, the time difference between the pulses applied to thecommon electrode 530 and the plurality of electrodes may be increased,thereby increasing the curvature formed in the liquid 530.

If an electrical signal is applied to the electrodes in the liquid lens500 with the switching element SWL turned on and electrically connectedwith the sensor unit 962 during the fourth period, a curvature may beformed in the liquid lens 500, and an electrical signal corresponding tothe curvature may be supplied to the sensor unit 962 via the switchingelement SWL.

Thus, the sensor unit 962 may sense the size or change in size of thearea of the boundary region Ac0 between the insulator on the electrodesand the electroconductive aqueous solutions 595 in the liquid lens 500or the capacitance of the boundary region Ac0, based on the electricalsignal from the liquid lens 500 during the ON period of the switchingelement SWL.

Accordingly, the controller 970 may calculate the curvature based on thesensed capacitance, and may determine whether or not the curvature hasreached the target curvature. If the curvature has reached the targetcurvature, the controller 970 may control a corresponding electricalsignal to be supplied to each of the electrodes.

As the electrical signal is supplied, the curvature of the liquid 530may be formed, and may be sensed immediately. Therefore, the curvatureof the liquid lens 500 may be identified quickly and accurately.

The lens driver 960 and the sensor unit 962 may be implemented by asingle module 965.

The lens driver 960 and the sensor unit 962, the controller 970, thepower supply 990, the AD converter 967, and the switching unit SWL shownin the figure may be implemented by a single system on chip (SOC).

As shown in FIGS. 4A to 4C, the liquid lens 500 may include a commonelectrode (COM) 520, a liquid 530 on the common electrode (COM) 520, andan electroconductive aqueous solution 595 on the liquid 530, and aplurality of electrodes (LA to LD) spaced apart from the liquid 530.

As illustrated in FIGS. 5A to 5E, the sensor unit 962 may sense the sizeor change in size of the area of the boundary region Ac0 between aninsulator on the electrodes and the electroconductive aqueous solution595 in the liquid lens 500, or may sense a capacitance correspondingthereto.

An analog signal related to the capacitance sensed by the sensor unit962 may be converted into a digital signal through an AD converter 967and input to the controller 970.

As illustrated in FIGS. 5A to 5E, as the curvature of the liquid lens500 increases, the area of the boundary region Ac0 increases, andconsequently the capacitance of the boundary region Ac0 increases.

In the present invention, it is assumed that the curvature is calculatedusing the capacitance sensed by the sensor unit 962.

The controller 970 may control the level of a voltage applied to theliquid lens 500 to increase or the pulse width to increase so as toincrease the curvature of the liquid lens 500.

As shown in FIG. 5C, when voltages of different levels or differentpulse widths are applied to a first electrode 540 a and a thirdelectrode 540 c among the plurality of electrodes (LA to LD) 540 a to540 d, a first capacitance of a first end portion Aca of the liquid 530and a second capacitance of a second end portion Acb of the liquid 530differ from each other.

Thus, the sensor unit 962 may sense the capacitances of the first endportion Aca and the second end portion Acb of the liquid 530,respectively.

By sensing the capacitances around the end operations of the liquid 530in the liquid lens 500, the curvature of the lens may be accuratelydetected.

In other words, by sensing the capacitances of a plurality of boundaryregions between the insulator on the electrodes and theelectroconductive aqueous solution 595 in the liquid lens 500, thecurvature of the liquid lens may be accurately detected.

When a constant voltage is applied to the common electrode (COM) 520 anda pulse is applied to the plurality of electrodes (LA to LD) 540 a to540 d, the sensor unit 962 may sense the capacitances for a plurality ofboundary regions between the insulator on the plurality of electrodes(LA to LD) 540 a to 540 d and the electroconductive aqueous solution595.

When a constant voltage is applied to the plurality of electrodes (LA toLD) 540 a to 540 d and a pulse is applied to the common electrode COM520, the capacitance of the boundary region between the insulator on thefirst electrode 520 and the electroconductive aqueous solution 595 maybe sensed.

The controller 970 may calculate the curvature of the liquid lens 500based on the capacitance sensed by the sensor unit 962.

The controller 970 may calculate the curvature of the liquid lens 500such that the curvature increases as the capacitance sensed by thesensor unit 962 increases.

Then, the controller 970 may control the liquid lens 500 to have atarget curvature.

The controller 970 may calculate the curvature of the liquid lens 500based on the capacitance sensed by the sensor unit 962, and output apulse width variation signal V based on the calculated curvature and thetarget curvature to the lens driver 960.

Then, the lens driver 960 may use the pulse width variation signal V andthe voltages Lv1 and Lv2 of the power supply 990 to output correspondingelectrical signals to the plurality of electrodes (LA to LD) 540 a to540 d and the common electrode (520).

Thus, as the capacitance of the liquid lens 500 is sensed and fed back,and an electrical signal is applied to the liquid lens 500 to vary thecurvature of the lens, the curvature of the lens may be varied quicklyand accurately.

The controller 970 may include an equalizer 972 to calculate a curvatureerror based on the calculated curvature and the target curvature, and apulse width variation controller 940 to generate and output a pulsewidth variation signal V based on the calculated curvature error Φ.

Accordingly, if the calculated curvature is greater than the targetcurvature, the controller 970 may control the duty of the pulse widthvariation signal V to increase or delay corresponding to the timedifference between a plurality of pulses applied to the liquid lens 500to increase, based on the calculated curvature error Φ. Accordingly, thecurvature of the liquid lens 500 may be varied quickly and accurately.

The controller 970 may receive focus information AF from the imageprocessor 930 and blurring information OIS from the gyro sensor 915, anddetermine the target curvature based on the focus information AF and theblurring information OIS.

Here, the update cycle of the determined target curvature is preferablylonger than the update cycle of the curvature calculated based on thesensed capacitance of the liquid lens 500.

Since the update cycle of the calculated curvature is shorter than theupdate cycle of the target curvature, the curvature of the liquid lens500 may be quickly changed to a desired curvature.

FIGS. 8A to 12B are views referred to in the description of FIG. 7.

FIG. 8A shows curvature change curves of the liquid lens 500 in theliquid curvature variation apparatus 800 of FIG. 6 and the lenscurvature variation apparatus 900 of FIG. 7.

Referring to FIG. 8A, GRo represents a curvature change curve of theliquid lens 500 in the lens curvature variation apparatus 800 of FIG. 6,and GRc represents a curvature change curve of the liquid lens 500 inthe lens curvature variation apparatus 900 of FIG. 7.

In particular, the figure illustrates a case where that a voltage forchanging the curvature to a target curvature is applied to the liquidlens 500 at time Tx, and is interrupted at time Ty.

It can be seen from the two curves that the change in curvature in thecase of the lens curvature variation apparatus 800 of FIG. 6 of the openloop system is slowly settled to a target diopter, and the change incurvature in the case of the lens curvature variation apparatus 900 ofFIG. 7 of the closed loop system is quickly and precisely settled,although not accurate.

The lens curvature variation apparatus 900 of FIG. 7 of the closed loopsystem may have a settling time shorter than the lens curvaturevariation apparatus 800 of FIG. 6 of the open loop system by about 70%.

Therefore, with the lens curvature variation apparatus 900 of FIG. 7 ofthe closed loop system, the curvature and the diopter may be formedquickly and accurately.

The diopter may correspond to the curvature of the liquid 530illustrated in FIGS. 5A to 5E. Accordingly, it may be defined that thediopter increases as the curvature of the liquid 530 increases, anddecreases as the curvature decreases.

For example, as shown in FIGS. 5A and 5B, when the curvature has a levelof +2 or +4, the diopter may be defined as having a level of +2 or +4corresponding to a convex lens. When the curvature has a level of 0, thediopter may be defined as having a level of 0 corresponding to the planelens. When the curvature has a level of −2 or −4 as shown in FIGS. 5Dand 5E, the diopter may be defined as having a level of −2 or −4corresponding to the concave lens.

FIG. 8B illustrates a timing chart for the common electrode COM, thefirst electrode LA, and the switching element SWL in the lens curvaturevariation apparatus 900 of FIG. 7.

Referring to FIG. 8B, during a period Dt1 between time T1 and time T3,the switching element SWL is turned on.

In order to sense the capacitance of the boundary region Ac0 through thesensor unit 962, a curvature is preferably formed in the liquid lens 500during the period Da between time T1 and time T3.

In order to ensure accuracy and stability of the sensing operation ofthe sensor unit 962 in the present invention, a pulse is applied to oneof the common electrode and the plurality of electrodes in the liquidlens 500 during the period Da between the time T1 and the time T3.

In particular, as shown in FIG. 8B, a pulse having a pulse width of Dt2may be applied to the common electrode 530 at time T2. Accordingly,after time T2, a curvature of the liquid lens 500 may be formed.

Accordingly, the sensor unit 962 may sense capacitances formed by theelectroconductive aqueous solution 595 and the electrodes according tothe size or change in size of the area of the boundary region Ac0between the insulator on the electrodes and the electroconductiveaqueous solution 595 in the liquid lens 500 during a period between timeT2 and time T3 in the period Da between time T1 and time T3.

During the period between time T2 and time T3, the sensor unit 962 maysense a potential difference or an electric current between theelectroconductive aqueous solution 595 and the electrodes correspondingto the size or change in size of the area of the boundary region Ac0between the insulator on the electrodes and the electroconductiveaqueous solution 595 in the liquid lens 500.

Next, at time T4, a pulse having a pulse width of Dt3 may be applied tothe first electrode LA.

That is, a high-level voltage may be applied to the common electrode COMat time point T2, and a high-level voltage may be applied to the firstelectrode LA at time point T4.

The curvature formed in the liquid 530 in the liquid lens 500 may bevaried according to a time difference DFF1 between the pulse applied tothe common electrode COM and the pulse applied to the first electrodeLA.

For example, as the time difference DFF1 between the pulses increases,the area of the boundary region Ac0 in which the electrodes contact theelectroconductive aqueous solution 595 may increase, and accordingly thecapacitance and the curvature may increase.

FIGS. 9A and 9B are diagrams illustrating various sensing methods forthe sensor unit.

FIG. 9A illustrates a sensor unit 962 a capable of sensing a capacitancewithout applying a separate additional pulse signal.

The sensor unit 962 a in the lens curvature variation apparatus 900 a ofFIG. 9A may operate in a continuous sensing manner.

To this end, the sensor unit 962 a of FIG. 9A may include a filter 1112to filter electrical signals from at least one of the plurality ofelectrodes (LA to LD) 540 a to 540 d, a peak detector 1114 to detect apeak of the electrical signal and a programmable gain amplifier (PGA)1116 to amplify the electrical signal from the peak detector 1114.

Specifically, the sensor unit 962 a of FIG. 9A may sense the capacitanceof the liquid lens 500 during a turn-on period of the switching elementSWL connected to at least one of the plurality of electrodes (LA to LD)540 a to 540 d.

Next, FIG. 9B illustrates a sensor unit 962 b capable of applying aseparate additional pulse signal to the common electrode (COM) 520 andsensing the capacitance during application of the additional pulsesignal.

The sensor unit 962 b in the lens curvature variation apparatus 900 b ofFIG. 9B may operate in a discrete sensing manner.

To this end, the sensor unit 962 b of FIG. 9B may include a conversionunit 1122 to convert the capacitance from at least one of the pluralityof electrodes (LA to LD) 540 a to 540 d into a voltage, and an amplifier1124 to amplify the voltage.

More specifically, during the turn-on period of the switching elementSWL connected to at least one of the electrodes (LA to LD) 540 a to 540d, an additional pulse signal may be applied to the common electrode(COM) 520, and the sensor unit 962 b of FIG. 9B may sense thecapacitance of the liquid lens 500 formed based on the additional pulsesignal.

A lens driver applicable to both of FIGS. 9A and 9B may be illustratedas shown in FIG. 10.

FIG. 10 is an exemplary internal circuit diagram of the lens driver ofFIG. 9A or 9B.

Referring to FIG. 10, the lens driver 960 a of FIG. 10 may include afirst driver 961 to drive a lens and a second driver 1310 to drive asensor.

The lens driver 960 a may further include a pulse width controller 1320to output a pulse width variation signal to the second driver 1310.

The pulse width controller 1320 may be provided in the pulse widthcontroller 940 of FIG. 7.

The first driver 961 may include first upper-arm and lower-arm switchingelements Sa and S′a connected in series to each other and secondupper-arm and lower-arm switching elements Sb and S′b connected inseries to each other.

Here, the first upper-arm and lower-arm switching elements Sa and S′aand the second upper-arm and lower-arm switching elements Sb and S′b areconnected in parallel to each other.

A power of level LV2 from the power supply 990 may be supplied to thefirst upper-arm switching element Sa and the second upper-arm switchingelement Sb.

The second driver 1310 may include third upper-arm and lower-armelements Sc and S′c connected in series to each other.

A power of level LV1, which is lower than level LV2, from the powersupply 990 may be supplied to the third upper-arm switching element Scto generate an additional pulse of a low level.

A voltage may be applied to the common electrode 520 through a nodebetween the first upper-arm switching element Sa and a first upper-armswitching element S′a or a node between the third upper-arm switchingelement Sc and the third lower-arm switching element S′c, and a voltagemay be applied to the first electrode (LA) 540 a through a node betweenthe second upper-arm switching element Sb and the second lower-armswitching element S′b.

FIG. 11A is an exemplary waveform diagram for explaining the operationof the lens driver 960 a of FIG. 10, and FIG. 11B is an exemplarydiagram referred to for explaining the operation of the sensor unit 962a of FIG. 9A.

Referring to FIG. 11A, during the period Dt1 between time T1 and timeT3, a high level is applied to the switching element SWL to turn on theswitching element SWL.

During the period Da between time T1 and time T3, low-level controlsignals LAP and LAM are applied to the switching element Sb and theswitching element S′b, respectively, and thus the switching element Sband the switching element S′b are floated.

The switching element Sb and the switching element S′b arecomplementarily turned on. However, both switching elements are floatedduring the period in which the switching element SWL is turned on.

At time T2, the control signal CMHP applied to the switching element Sais switched to the high level and the control signal CMHM applied to theswitching element S′a is switched to the low level.

The switching element Sa and the switching element S′a are always turnedon complementarily.

At time T2, the control signal CMHP applied to the switching element Sais switched to the high level. At time T4, the control signal LApapplied to the switching element Sb is switched to the high level.

A pulse having a pulse width of Dt2 may be applied at time T2 during theperiod Da between time T1 and time T3. Accordingly, after time T2, thecurvature of the liquid lens 500 may be formed.

Accordingly, during the period between time T2 and time T3 in the periodDa between time T1 and time T3, the sensor unit 962 may sense acapacitance corresponding to the size or change in size of the area ofthe boundary region Ac0 between the insulator on the electrodes and theelectroconductive aqueous solution 595 in the liquid lens 500.

Specifically, during the period between time T2 and time T3, a signal oflevel Lv3 may be applied to the filter 1112, the peak detector 114 maydetect the signal, and the PGA 1116 may amplify the signal. Thus, duringthe period between time T2 and time T3, the capacitance corresponding tothe size or change in size of the area of the boundary region Ac0between the insulator on the electrodes and the electroconductiveaqueous solution 595 in the liquid lens 500 may be sensed.

A high-level voltage may be applied to the common electrode COM at timeT2, and a high-level voltage may be applied to the first electrode LA attime T4.

The curvature formed in the liquid 530 in the liquid lens 500 may bevaried according to a time difference DFF1 between the pulse applied tothe common electrode COM and the pulse applied to the first electrodeLA.

For example, as the time difference DFF1 between the pulses increases,the area of the boundary region Ac0 in which the electrodes contact theelectroconductive aqueous solution 595 may increase, and accordingly thecapacitance may increase.

In the example of FIG. 11A, the second driver 1310 of FIG. 10 does notoperate.

Next, the common electrode 520 is grounded at time T5, and the firstelectrode (LA) 540 a is grounded at time T6. Thereafter, the operationsat times T1 and T2 are repeated at times T7 and T8.

FIG. 11C is another exemplary waveform diagram illustrating theoperation of the lens driver 960 a of FIG. 10, and FIG. 11D is a diagramillustrating the operation of the sensor unit 962 a of FIG. 9A.

FIG. 11C is similar to the waveform diagram of FIG. 11A except thatcontrol signals CMLP and CMLM for operation of the switching elements Scand S′c in the second driver 1310 of FIG. 10 are provided.

The sensor unit SWL is turned on during the period between T1 and T2 andis turned off after T2.

At time T2, the control signal CMHP applied to the switching element Sais switched to the high level. At time T3, the control signal LApapplied to the switching element Sb is switched to the high level.

During the period between T1 and T2, the switching element Sc may beturned on. Then, as shown in FIG. 11D, an additional pulse SMP having alevel Lv1 supplied from the power supply 990 b may be applied to thecommon electrode COM.

Accordingly, during the period Da between time T1 and time T2, thesensor unit 962 may sense a capacitance corresponding to the size orchange in size of the area of the boundary region Ac0 between theinsulator on the electrodes and the electroconductive aqueous solution595 in the liquid lens 500.

Specifically, during the period between time T1 and T2, a signal of alevel Lv5 lower than the level Lv3 may be applied to the filter 1112,the peak detector 114 may detect the signal, and the PGA 1116 mayamplify the signal. Thus, during the period between time T1 and time T2,the capacitance corresponding to the size or change in size of the areaof the boundary region Ac0 between the insulator on the electrodes andthe electroconductive aqueous solution 595 in the liquid lens 500 may besensed.

Next, at time T3, a pulse SLP having a pulse width of Dt2 and a levelLv2 higher than the level Lv1 may be applied to the common electrodeCOM.

Next, at time T4, a pulse having a pulse width of Dt3 may be applied tothe first electrode LA.

The curvature formed in the liquid 530 in the liquid lens 500 may bevaried according to a time difference DFF1 between the pulse applied tothe common electrode COM and the pulse applied to the first electrodeLA.

For example, as the time difference DFF1 between the pulses decreases,the area of the boundary region Ac0 in which the electrodes contact theelectroconductive aqueous solution 595 may increase, and accordingly thecapacitance may increase. As a result, the curvature may decrease.

FIG. 11E is another exemplary waveform diagram illustrating theoperation of the lens driver 960 a of FIG. 10, and FIG. 11F is a diagramillustrating the operation of the sensor unit 962 b of FIG. 9B.

FIG. 11E is similar to the waveform diagram of FIG. 11C. However, unlikeFIG. 11C, during the period from T1 to T2, control signals CMLP and CMLMfor operating the switching elements Sc and S′c in the second driver1310 of FIG. 10 have a plurality of pulses instead of a single pulse.

Thus, as shown in FIG. 11F, a plurality of pulses SMPa is applied to thecommon electrode COM during the period from T1 to T2.

Accordingly, during the period Da between time T1 and time T2, thesensor unit 962 may sense a capacitance corresponding to the size orchange in size of the area of the boundary region Ac0 between theinsulator on the electrodes and the electroconductive aqueous solution595 in the liquid lens 500.

Specifically, during the period between time T1 and time T2, a pluralityof pulse signals Lv3 may be applied to the C2V converter 1122, and theSC amplifier 1124 may amplify the plurality of pulse signals. Thus,during the period between time T1 and time T2, the capacitancecorresponding to the size or change in size of the area of the boundaryregion Ac0 between the insulator on the electrodes and theelectroconductive aqueous solution 595 in the liquid lens 500 may besensed. In particular, a voltage signal corresponding to the capacitancemay be output as the output of the sensor section 962.

FIG. 13A is an exemplary internal block diagram of a camera according toanother embodiment of the present invention.

Referring to FIG. 13A, the camera 195 n and the lens curvature variationapparatus 900 b shown in FIG. 13A are similar to the camera 195 m andthe lens curvature variation apparatus 900 shown in FIG. 7, except thatthe capacitances of the end portions of a plurality of liquids 530corresponding to a plurality of electrodes (LA to LD) 540 a to 540 d aresensed.

To this end, a low-level voltage is applied to the common electrode(COM) 520, and a pulse signal may be applied to the plurality ofelectrodes (LA to LD) 540 a to 540 d.

Preferably, to allow operation of the sensor unit 962, a plurality ofswitching elements SWLa to SWLd is provided between conductive lines CAto CD, which are connected between the plurality of electrodes (LA toLD) and the liquid lens 500, and the sensor unit 962.

The sensor unit 962 may sense the capacitances of the boundary regionsbetween the insulator on the plurality of electrodes (LA to LD) 540 a to540 d and the electroconductive aqueous solution based on the pulsesignals applied to the plurality of electrodes (LA to LD) 540 a to 540 dduring a period in which the plurality of switching elements SWLa toSWLd is turned on, and may transmit the sensed capacitances to thecontroller 970.

Accordingly, the capacitances of a plurality of boundary regions of theliquid lens 500 may be sensed.

Further, the camera 195 n of FIG. 13A may vary the voltages applied tothe plurality of electrodes (LA to LD) 540 a to 540 d for blurringcorrection to form an asymmetric curvature. Blurring correction may beperformed accurately and quickly.

FIG. 13B is an exemplary internal block diagram of a camera according toyet another embodiment of the present invention.

Referring to FIG. 13B, the camera 195 o and the lens curvature variationapparatus 900 c shown in FIG. 13B are similar to the camera 195 m andthe lens curvature variation apparatus 900 shown in FIG. 7, except thatthe capacitances of the end portions of the liquid corresponding to theplurality of electrodes (LA to LD) 540 a to 540 d are sensed.

To this end, a low-level voltage may be applied to the plurality ofelectrodes (LA to LD) 540 a to 540 d, and a pulse signal may be appliedto the common electrode (COM)

Preferably, to allow the operation of the sensor unit 962, a switchingelement SWL is provided between a conductive line CM, which is connectedbetween the common electrode COM and the liquid lens 500, and the sensorunit 962, instead of the conductive lines CA to CD connected between theplurality of electrodes (LA to LD) 540 a to 540 d and the liquid lens500.

The sensor unit 962 may sense the capacitance of the boundary regionbetween the insulator on the electrodes and the electroconductiveaqueous solution based on the pulse signal applied to the commonelectrode COM during a period in which the switching element SWL isturned on, and may transmit the sensed capacitance to the controller970.

Accordingly, the capacitance of the boundary region of the liquid lens500 may be sensed.

Further, the camera 195 o of FIG. 13B may form an asymmetric curvaturein response to blurring correction, and therefore the blurringcorrection may be performed accurately and quickly.

The lens curvature variation apparatus 900 described with reference toFIGS. 9 to 15B may be employed for various electronic devices such asthe mobile terminal, a vehicle, a TV, a drone, a robot, and a robotcleaner.

The method of operating the lens curvature variation apparatus of thepresent invention may be implemented as a code that can be read by aprocessor on a recording medium readable by a processor included in thelens curvature variation apparatus. The processor-readable recordingmedium may include all kinds of recording apparatuses in which datareadable by the processor is stored. Examples of the recording mediumreadable by the processor include a ROM, a RAM, a CD-ROM, a magnetictape, a floppy disk, and an optical data storage device, and may also beimplemented in the form of a carrier wave such as transmission over theInternet. In addition, the processor-readable recording medium may bedistributed over network-connected computer systems such that codereadable by the processor in a distributed fashion may be stored andexecuted.

Although the preferred embodiments of the present invention have beendisclosed for illustrative purposes, those skilled in the art willappreciate that various modifications, additions and substitutions arepossible, without departing from the scope and spirit of the inventionas disclosed in the accompanying claims.

INDUSTRIAL APPLICABILITY

The present invention is applicable to a lens curvature variationapparatus capable of quickly and accurately sensing the curvature of alens.

1. A lens curvature variation apparatus for varying a curvature of aliquid lens based on an applied electrical signal, the lens curvaturevariation apparatus comprising: a lens driver to apply the electricalsignal to the liquid lens; a sensor unit to sense the curvature of theliquid lens formed based on the electrical signal; and a controller tocontrol the lens driver to form a target curvature of the liquid lensbased on the sensed curvature, wherein the sensor unit senses a size ofan area of a boundary region between an insulator on an electrode and anelectroconductive aqueous solution in the liquid lens or a change in thesize.
 2. The lens curvature variation apparatus according to claim 1,wherein the sensor unit senses a capacitance formed by theelectroconductive aqueous solution and the electrode corresponding tothe size of the area of the boundary region between the insulator on theelectrode and the electroconductive aqueous solution in the liquid lensor the change in the size.
 3. The lens curvature variation apparatusaccording to claim 2, wherein the sensor unit converts the sensedcapacitance into a voltage signal.
 4. The lens curvature variationapparatus according to claim 2, comprising: a converter to convert asignal related to the capacitance sensed by the sensor unit into adigital signal.
 5. The lens curvature variation apparatus according toclaim 1, wherein the sensor unit senses a potential difference or acurrent between the electroconductive aqueous solution and the electrodecorresponding to the size of the area of the boundary region between theinsulator on the electrode and the electroconductive aqueous solution inthe liquid lens or the change in the size.
 6. The lens curvaturevariation apparatus according to claim 1, further comprising: aplurality of conductive lines for supplying a plurality of electricalsignals output from the lens driver to the liquid lens; and a switchingelement disposed between any one of the plurality of conductive linesand the sensor unit.
 7. The lens curvature variation apparatus accordingto claim 6, wherein the sensor unit senses the size of the area of theboundary region between the insulator on the electrode and theelectroconductive aqueous solution in the liquid lens or the change inthe size during an ON period of the switching element.
 8. The lenscurvature variation apparatus according to claim 6, wherein the sensorunit senses the size of the area of the boundary region between theinsulator on the electrode and the electroconductive aqueous solution inthe liquid lens or the change in the size, while a pulse signal isapplied to at least one of the plurality of conductive lines and theswitching element is turned on.
 9. The lens curvature variationapparatus according to claim 1, wherein the liquid lens comprises: acommon electrode; a plurality of electrodes spaced apart from the commonelectrode; and a liquid and the electroconductive aqueous solutiondisposed between the common electrode and the plurality of electrodes.10. The lens curvature variation apparatus according to claim 9, whereinthe liquid lens comprises: a plurality of insulators for insulating theplurality of electrodes.
 11. The lens curvature variation apparatusaccording to claim 2, wherein the curvature of the liquid lens increasesas the capacitance increases.
 12. The lens curvature variation apparatusaccording to claim 9, wherein, when different voltages are applied to afirst capacitance and a second electrode among the plurality ofelectrodes, a first capacitance of a first end portion of the liquid isdifferent from a second capacitance of a second end portion of theliquid.
 13. The lens curvature variation apparatus according to claim 9,wherein the curvature of the liquid lens increases as a time differencebetween a first pulse applied to the common electrode and a second pulseapplied to any one of the plurality of electrodes increases.
 14. Thelens curvature variation apparatus according to claim 9, wherein, whilea pulse is applied to the common electrode and at least one of theplurality of electrodes, the controller calculates the curvature of theliquid lens based on the capacitance sensed by the sensor unit, andoutputs a pulse width variation signal to the lens driver based on thecalculated curvature and the target curvature.
 15. The lens curvaturevariation apparatus according to claim 14, wherein, when the calculatedcurvature is less than the target curvature, the controller controls aduty of the pulse width variation signal to increase.
 16. The lenscurvature variation apparatus according to claim 14, wherein thecontroller comprises: an equalizer to calculate a curvature error basedon the calculated curvature and the target curvature; and a pulse widthvariation controller to generate and output the pulse width variationsignal based on the calculated curvature error.
 17. The lens curvaturevariation apparatus according to claim 9, wherein the sensor unitcomprises: a filter to filter an electrical signal from at least one ofthe plurality of electrodes; a peak detector to detect a peak of theelectrical signal from the filter; and an amplifier to amplify theelectrical signal from the peak detector.
 18. The lens curvaturevariation apparatus according to claim 9, wherein a pulse signal isapplied to the common electrode during a turn-on period of a switchingelement connected to at least one of the plurality of electrodes,wherein the sensor unit senses a capacitance of a boundary regionbetween an insulator on the common electrode and an electroconductiveaqueous solution in the liquid lens during a pulse signal applicationperiod in the turn-on period of the switching element.
 19. The lenscurvature variation apparatus according to claim 9, wherein the sensorunit comprises: a conversion unit to convert a capacitance from at leastone of the plurality of electrodes into a voltage; and an amplifier toamplify the voltage.